Kinetics of the reaction between chloroform and 2,5-dimethylpyrrole in the vapour phase

A kinetic study of the reaction between chloroform and 2,5-dimethylpyrrole in a continuous flow vapour phase system at 733 K showed the rate to be first order with respect to chloroform.     

Investigations of interfacial reactions of Sn–Zn based and Sn–Ag–Cu lead-free solder alloys as replacement for Sn–Pb solder

The interfacial reactions of Sn–Zn based solders and a Sn–Ag–Cu solder have been compared with a eutectic Sn–Pb solder. During reflow soldering different types of intermetallic compounds (IMCs) are found at the interface. The morphologies of these IMCs are quite different for different solder compositions. As-reflowed, the growth rates of IMCs in the Sn–Zn based solder are higher than in the Sn–Ag–Cu and Sn–Pb solders. Different types of IMCs such as γ-Cu₅Zn₈, β-CuZn and a thin unknown Cu–Zn layer are formed in the Sn–Zn based solder but in the cases of Cu/Sn–Pb and Cu/Sn–Ag–Cu solder systems Cu₆Sn₅ IMC layers are formed at the interface. Cu₆Sn₅ and Cu₃Sn interfacial IMCs are formed in the early stages of 10 min reflow due to the limited supply of Sn from the Sn–Pb solder. The spalling of Cu–Sn IMCs is observed only in the Sn–Ag–Cu solder. The size of Zn platelets is increased with an increase of reflow time for the Cu/Sn–Zn solder system. In the case of the Sn–Zn–Bi solder, there is no significant increase in the Zn-rich phases with extended reflow time. Also, Bi offers significant effects on the wetting, the growth rate of IMCs as well as on the size and distribution of Zn-rich phases in the β-Sn matrix. No Cu–Sn IMCs are found in the Sn–Zn based solder during 20 min reflow. The consumption of Cu by the solders are ranked as Sn–Zn–Bi > Sn–Ag–Cu > Sn–Zn > Sn–Pb. Despite the higher Cu-consumption rate, Bi-containing solder may be a promising candidate for a lead-free solder in modern electronic packaging taking into account its lower soldering temperature and material costs.     

SwCS: Section-Wise Content Similarity Approach to Exploit Scientific Big Data

The growing collection of scientific data in various web repositories is referred to as Scientific Big Data, as it fulfills the four “V’s” of Big Data–-volume, variety, velocity, and veracity. This phenomenon has created new opportunities for startups; for instance, the extraction of pertinent research papers from enormous knowledge repositories using certain innovative methods has become an important task for researchers and entrepreneurs. Traditionally, the content of the papers are compared to list the relevant papers from a repository. The conventional method results in a long list of papers that is often impossible to interpret productively. Therefore, the need for a novel approach that intelligently utilizes the available data is imminent. Moreover, the primary element of the scientific knowledge base is a research article, which consists of various logical sections such as the Abstract, Introduction, Related Work, Methodology, Results, and Conclusion. Thus, this study utilizes these logical sections of research articles, because they hold significant potential in finding relevant papers. In this study, comprehensive experiments were performed to determine the role of the logical sections-based terms indexing method in improving the quality of results (i.e., retrieving relevant papers). Therefore, we proposed, implemented, and evaluated the logical sections-based content comparisons method to address the research objective with a standard method of indexing terms. The section-based approach outperformed the standard content-based approach in identifying relevant documents from all classified topics of computer science. Overall, the proposed approach extracted 14% more relevant results from the entire dataset. As the experimental results suggested that employing a finer content similarity technique improved the quality of results, the proposed approach has led the foundation of knowledge-based startups.     

Synthesis of Nanozeolites/Carbon Composites for the Adsorptionof Bivalent Copper

Linde type A nanozeolite particles were successfully synthetized and supported over carbon-based materials in order to produce a hierarchical structured composite using a method based on the surface chemistry modification of carbon supports. Carbonaceous supports, exhibiting wide voids and openings, have been prepared using residues from agricultural activities such as cherry stones and hazelnut shells. Carbons using thermal treatment were produced and they were conditioned using polydiallyldimethylammonium chloride in order to promote the zeolites attachment onto the carbon surface. Supports were successfully covered with a consistent layer of zeolites and results showed that the chemical surface modification had a positive effect on the deposition of zeolites on carbons. In addition, copper adsorption experiments using these materials showed that the distribution of zeolite on a support improved their uptake efficiency from 73.80 to 288.22 mg·g^–1 for synthetic nanozeolite A. In addition, kinetic results showed that materials follow the pseudo-second order equation with high degree of correlation (R² > 0.97) suggesting that chemisorption is the rate-limiting step and it is more dependent on solid capacity than ion concentration in solution. Finally, equilibrium adsorption results showed a good adjustment of Langmuir model (R² = 0.96).     

Pricing strategies and categories for LTE networks

Long Term Evolution (LTE) systems will provide a large number of users with various high quality wireless Internet services including but not limited to voice over IP, real-time gaming, multimedia streaming and several others. A suitable pricing policy is an important component in order to bring benefits to both the operators and the customers. In fact, through this, the operator can efficiently manage the radio resources of cellular networks. For different types of services, the operator can maintain user Quality of Service and through which, the revenue can be optimized. This article analyzes various possible LTE pricing schemes, including the one proposed, based on different criteria: network load and congestion, operator revenue, traffic differentiation and user categorization. We provide comparative graphs to highlight the pros and cons of the studied pricing strategies. We highlight the importance for the operator to move from the often used flat-rate style policies towards more dynamic pricing strategies taking into account the user and service classes.     

ZGLS: a novel flat quorum-based and reliable location management protocol for VANETs

In location management services, a destination advertises its position attributes to a set of vehicles called location servers while, a source obtains these attributes from such location servers to track destination. The location management techniques in VANET have been categorized into flooding-based, flat hashing-based, hierarchical hashing-based and hierarchical quorum-based techniques. In flooding-based location service, destination information is flooded to the entire network which results into high congestion, low throughput and non-scalable network. In flat hashing, a global hash function is applied to compute location servers of each destination which results into higher delay, drop and signaling overhead in large VANETs. In hierarchical hashing, global hash function computes location servers of destination in hierarchical order. It therefore suffers from handover signaling between servers, high load on the top hierarchy and location query delay when source and destination are apart. In hierarchical quorum-based, location servers are identified cluster-wise and therefore it also suffers from the problems similar to hierarchical techniques. To overcome these problems, ZoomOut Geographic Location Service (ZGLS) protocol is proposed which introduces flat quorum-based location management service. In contrast to the aforementioned techniques, the novelty of ZGLS lies in the fact that it has shifted the location server role from hashing-based or clustering-based geographic areas to few 1-hop neighbours, called relatives. The proposed protocol creates a chain of relatives to provide positioning and tracking service. To evaluate signalling overhead, timeliness and the reliability of update and query packets, ZGLS is compared with RLSMP and HRHLS through ns-2 simulations. The results reveal that ZGLS stands out as a better choice for large-scale sparse and dense VANETs.     

Processing issues of color mismatch: Rheological characterization of polycarbonate blends

In this study, resins of two Lexan polycarbonates with and without the addition of pigments and additives were blended in a Thermo Haake Mini Lab II twin‐screw micro compounder. The blends were rheologically characterized using dynamic strain sweep mode, dynamic frequency sweep mode, and steady rate sweep mode. The tests were performed at 230°C, 255°C, and 280°C under nitrogen atmosphere. The obtained results present that the variation in polycarbonate resin proportions and temperature significantly affected the rheological properties. The focus was extended on the polycarbonate blend having composition of two resins 30/70% and the obtained viscosity data was correlated to color changes. POLYM. ENG. SCI., 55:1994–2001, 2015. © 2014 Society of Plastics Engineers     

Characterization of supercritical fluid extrusion processed rice–soy crisps fortified with micronutrients and soy protein

Protein and micro-nutrients enriched rice–soy crisps (RSC) were prepared using supercritical fluid extrusion and their impact on quality attributes was determined. A low-shear, twin screw, co-rotating extruder was used to produce puffed RSC using supercritical CO₂ (SC-CO₂), which served as an expansion agent during the process carried out at lower temperatures (∼100 °C) compared to conventional steam based extrusion (∼130–180 °C). The fortified RSC contained 25–40 g/100 g soy protein and four micronutrients (iron, zinc, vitamin A and C) at the recommended daily values in 100 g product. The RSC were analyzed for physical characteristics and nutrient composition. The increasing soy protein fortification from 25 to 40 g/100 g reduced the crisps expansion ratio (4.27–2.95), crispiness (15.0–9.5), and increased piece density (0.21–0.27 g/cm³), bulk density (0.17–0.22 g/cm³) and hardness (76.39–129.05 N). The nutrient fortification improved protein (334–568%) and dietary fiber (571–901%) and the extrusion process retained all of the added minerals and about 50% retention of vitamin A and C in the final products. The SC-CO₂ assisted extrusion is an effective process-based approach to produce low-moisture, fortified crispy products. These products are appropriate for consumption as nutribars especially for school lunch programs in developing countries to reduce malnutrition through process based nutrient fortification approaches.     

The Relationship between COVID-19 and Hypothalamic–Pituitary–Adrenal Axis: A Large Spectrum from Glucocorticoid Insufficiency to Excess—The CAPISCO International Expert Panel

Coronavirus disease 2019 (COVID-19) is a highly heterogeneous disease regarding severity, vulnerability to infection due to comorbidities, and treatment approaches. The hypothalamic–pituitary–adrenal (HPA) axis has been identified as one of the most critical endocrine targets of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that might significantly impact outcomes after infection. Herein we review the rationale for glucocorticoid use in the setting of COVID-19 and emphasize the need to have a low index of suspicion for glucocorticoid-induced adrenal insufficiency, adjusting for the glucocorticoid formulation used, dose, treatment duration, and underlying health problems. We also address several additional mechanisms that may cause HPA axis dysfunction, including critical illness-related corticosteroid insufficiency, the direct cytopathic impacts of SARS-CoV-2 infection on the adrenals, pituitary, and hypothalamus, immune-mediated inflammations, small vessel vasculitis, microthrombotic events, the resistance of cortisol receptors, and impaired post-receptor signaling, as well as the dissociation of ACTH and cortisol regulation. We also discuss the increased risk of infection and more severe illness in COVID-19 patients with pre-existing disorders of the HPA axis, from insufficiency to excess. These insights into the complex regulation of the HPA axis reveal how well the body performs in its adaptive survival mechanism during a severe infection, such as SARS-CoV-2, and how many parameters might disbalance the outcomes of this adaptation.     

Ultrasonic-Assisted Synthesis of Benzofuran Appended Oxadiazole Molecules as Tyrosinase Inhibitors: Mechanistic Approach through Enzyme Inhibition,Molecular Docking,Chemoinformatics, ADMET and Drug-Likeness Studies

Furan-oxadiazole structural hybrids belong to the most promising and biologically active classes of oxygen and nitrogen containing five member heterocycles which have expanded therapeutic scope and potential in the fields of pharmacology, medicinal chemistry and pharmaceutics. A novel series 5a–j of benzofuran-oxadiazole molecules incorporating S-alkylated amide linkage have been synthesized using ultrasonic irradiation and screened for bacterial tyrosinase inhibition activity. Most of the synthesized furan-oxadiazole structural motifs exhibited significant tyrosinase inhibition activity in the micromolar range, with one of the derivatives being more potent than the standard drug ascorbic acid. Among the tested compounds, the scaffold 5a displayed more tyrosinase inhibition efficacy IC₅₀ (11 ± 0.25 μM) than the ascorbic acid IC₅₀ (11.5 ± 0.1 μM). Compounds 5b, 5c and 5d efficiently inhibited bacterial tyrosinase with IC₅₀ values in the range of 12.4 ± 0.0–15.5 ± 0.0 μM. The 2-fluorophenylacetamide containing furan-oxadiazole compound 5a may be considered as a potential lead for tyrosinase inhibition with lesser side effects as a skin whitening and malignant melanoma anticancer agent.